What is an Ovarian Cyst?
By William M. Rich MD
Ovarian cysts are frequently encountered. Every menstruating woman develops an ovarian cyst every cycle. This is called a follicle cyst and it contains an egg. The ovary is directed by the pituitary gland in the brain. The pituitary gland produces
the hormone Follicle Stimulating Hormone (FSH) and releases it into the blood stream. The ovary responds to FSH by maturing an egg. While doing this, the ovary makes the hormone estrogen. Estrogen stimulates the lining of the uterus to grow. The ovary
matures the egg in a small cyst that eventually grows to be about 2cm in diameter.
At the proper time the pituitary produces and releases another hormone called Luteinizing Hormone (LH). LH causes the cyst to break and release the egg. This is called ovulation. The remnant of the follicle cyst is called the corpus luteum and begins to produce the other ovarian hormone, progesterone. Progesterone converts the lining of the uterus to accept the pregnancy. If a pregnancy does not occur that cycle then the ovary stops producing progesterone. When the progesterone level falls, the lining of the uterus falls off as the menstrual period. Then the cycle starts all over again: estrogen, ovulation, progesterone and then the menstrual period.
Sometimes the ovary does not ovulate and the follicle cyst persists. It continues to enlarge and can become as big as a baseball. Eventually it will break and the woman may not even be aware that this has happened. The period may be delayed because there is no progesterone phase of the cycle to respond to. If for some reason the enlarged follicle cyst is detected during this time the woman will be told she has a cyst on her ovary. The corpus luteum can also become cystic and this may also be
detected. What is this cyst? Is it a cancer? What is to be done?
If a sonogram shows this to be a simple cyst without any internal structures.
If it is only on one side.
If it is less than 4-5inchs in diameter.
If it occurs in an ovulating woman or an early pregnant woman.
If there are no associated findings such as nodules or fluid in the pelvis.
If there are no major symptoms of pain.
Then wait.
Schedule a re-examination for 4 weeks. If it is gone or getting smaller then it was a functional cyst: either a follicle cyst or a corpus luteum cyst. Nothing more needs to be done.
Women on birth control pills should not develop functional cysts. Although some women ovulate on their pills, the function of the pill is to suppress ovulation. Premenarchal and postmenopausal women should not develop functional cysts. Women in these groups with a cyst as well as those with a complex or a solid cyst will
have to be evaluated surgically. This is the only way to make sure that the cyst is or is not a cancer. A Ca-125 test is of no value. It can be elevated for a variety of reasons and a normal value is meaningless. A surgical evaluation must be done. Most of the "cysts" will be shown surgically to be things other than cancers.
Nonmalignant Causes of Ovarian "Cysts":
Benign neoplastic ovarian cystadenomas.
Benign teratomas such as a dermoid.
Cysts of structures next to the ovary.
Fluid filled Fallopian tubes.
Infections in the tubes and or ovaries.
Endometriosis and endometrial ovarian cysts.
Fibroid tumors of the uterus that are on a stalk and appear to be ovarian.
Abcess of the appendix.
Abcess of a colon diverticulum.
In many instances, the surgical evaluation can be accomplished by laparoscopy. Laparoscopy is an outpatient procedure, but will in most cases, require a general anesthetic and a trip to the operating room.
Most ovarian "cysts" are not cancers.
William M. Rich, MD
Clinical Professor of Obstetrics and Gynecology
University of California San Francisco
Director of Gynecologic Oncology
Valley Medical Center
Fresno, Ca.
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Last updated
2 July 1996
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